A new study from researchers in Spain finds intrauterine devices (IUDs) might actually protect against cervical cancer. The authors report their findings in The Lancet Oncology, and say theirs is the largest epidemiological study to date on the issue, involving over 20,000 women. The findings showed that women with a history of using IUDs had almost half the risk of developing cervical cancer compared with women who had never used IUDs.

We asked Edgar P. Simard, PhD, MPH, senior epidemiologist at the American Cancer Society for some comments about the study.

“Castellsague and colleagues’ thoughtful analysis accounted for a number of factors known to influence cervical cancer risk including the presence of HPV DNA, frequency of previous Pap smear screening, and lifetime number of sexual partners. They found an overall 45% decreased risk of cervical cancer among women who had ever used an IUD relative to those who had never used one. These provocative findings were consistent regardless of histologic subtype and years of IUD use.

“Notably, IUD use did not protect against HPV infection but did result in a reduced risk of cervical cancer, suggesting that it favorably influences persistence of HPV infection. Although the precise mechanism is unclear, the authors postulate that microtrauma to the cervix and surrounding tissue induced during the insertion and removal of IUDs produces an immune response protecting against progression of precancerous lesions to cervical cancer.

“Additional studies are warranted to determine whether the protective effect is similar for copper IUDs and hormone-reducing IUDs and to determine the precise cellular and immunologic mechanisms by which IUDs apparently reduce cervical cancer risk. It is also unclear if women with pre-existing cervical abnormalities (which can progress to cancer) might also benefit from IUD use.

“IUD use is not very common in the US. Also, routine Pap smears have resulted in historical declines in cervical cancer and future declines may be attributed to HPV vaccination of girls during childhood. In other parts of the world where IUD use and cervical cancer are more common, these finding should be confirmed. Despite the importance of these results, routine cervical cancer screenings and HPV vaccination remain the most prudent methods of cervical cancer prevention.”